Localization of pSmad1 and pSmad2 on late endosomes in P3 mouse lens cells. A. Rab7 (red), pSmad1 (green), TOTO-1 (blue). B. Rab7 (red), pSmad2 (green), TOTO-1 (blue). Both pSmad1 and pSmad2 co-localize with Rab7 on a small number of cytoplasmic vesicles. Nuclear staining for pSmad1 and pSmad2 is mostly obscured by the strong fluorescence of the nucleic acid stain, TOTO-1.